 /*******************************************************************************
  * Copyright (c) 2000, 2007 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.texteditor.quickdiff;

 import java.util.Iterator ;
 import java.util.List ;

 import org.eclipse.jface.action.IAction;
 import org.eclipse.jface.action.IMenuListener;
 import org.eclipse.jface.action.IMenuManager;
 import org.eclipse.jface.action.MenuManager;
 import org.eclipse.jface.action.Separator;
 import org.eclipse.jface.viewers.ISelection;

 import org.eclipse.ui.IEditorActionDelegate;
 import org.eclipse.ui.IEditorPart;
 import org.eclipse.ui.IWorkbenchActionConstants;
 import org.eclipse.ui.texteditor.ITextEditor;
 import org.eclipse.ui.texteditor.ITextEditorExtension;
 import org.eclipse.ui.texteditor.ITextEditorExtension3;
 import org.eclipse.ui.texteditor.IUpdate;

 import org.eclipse.ui.internal.texteditor.quickdiff.QuickDiffMessages;
 import org.eclipse.ui.internal.texteditor.quickdiff.QuickDiffRestoreAction;
 import org.eclipse.ui.internal.texteditor.quickdiff.ReferenceSelectionAction;
 import org.eclipse.ui.internal.texteditor.quickdiff.RestoreAction;
 import org.eclipse.ui.internal.texteditor.quickdiff.RevertBlockAction;
 import org.eclipse.ui.internal.texteditor.quickdiff.RevertLineAction;
 import org.eclipse.ui.internal.texteditor.quickdiff.RevertSelectionAction;

 /**
  * Action to toggle the line number bar's quick diff display. When turned on, quick diff shows
  * the changes relative to the saved version of the file.
  *
  * @since 3.0
  */
 public class QuickDiffToggleAction implements IEditorActionDelegate, IUpdate {

     /** The editor we are working on. */
     ITextEditor fEditor= null;

     /** Our UI proxy action. */
     IAction fProxy;

     /** The restore actions associated with this toggle action. */
     QuickDiffRestoreAction[] fRestoreActions=
         new QuickDiffRestoreAction[] {
             new RevertSelectionAction(fEditor, true),
             new RevertBlockAction(fEditor, true),
             new RevertLineAction(fEditor, true),
             new RestoreAction(fEditor, true),
         };

     /** The menu listener that adds the ruler context menu. */
     private IMenuListener fListener= new IMenuListener() {
         /** Group name for additions, in CompilationUnitEditor... */
         private static final String GROUP_ADD= "add"; //$NON-NLS-1$
 /** Group name for debug contributions */
         private static final String GROUP_DEBUB= "debug"; //$NON-NLS-1$
 private static final String GROUP_QUICKDIFF= "quickdiff"; //$NON-NLS-1$
 private static final String MENU_ID= "quickdiff.menu"; //$NON-NLS-1$
 private static final String GROUP_RESTORE= "restore"; //$NON-NLS-1$

         public void menuAboutToShow(IMenuManager manager) {
             // update the toggle action itself
 update();

             IMenuManager menu= (IMenuManager)manager.find(MENU_ID);
             // only add menu if it isn't there yet
 if (menu == null) {
                 /* HACK: pre-install menu groups
                  * This is needed since we get the blank context menu, but want to show up
                  * in the same position as the extension-added QuickDiffToggleAction.
                  * The extension is added at the end (naturally), but other menus (debug, add)
                  * don't add themselves to MB_ADDITIONS or alike, but rather to the end, too. So
                  * we pre-install their respective menu groups here.
                  */
                 if (manager.find(GROUP_DEBUB) == null)
                     manager.insertBefore(IWorkbenchActionConstants.MB_ADDITIONS, new Separator(GROUP_DEBUB));
                 if (manager.find(GROUP_ADD) == null)
                     manager.insertAfter(IWorkbenchActionConstants.MB_ADDITIONS, new Separator(GROUP_ADD));
                 if (manager.find(GROUP_RESTORE) == null)
                     manager.insertAfter(GROUP_ADD, new Separator(GROUP_RESTORE));
                 if (manager.find(GROUP_QUICKDIFF) == null)
                     manager.insertAfter(GROUP_RESTORE, new Separator(GROUP_QUICKDIFF));

                 // create quickdiff menu
 menu= new MenuManager(QuickDiffMessages.quickdiff_menu_label, MENU_ID);
                 List descriptors= new QuickDiff().getReferenceProviderDescriptors();
                 for (Iterator it= descriptors.iterator(); it.hasNext();) {
                     ReferenceProviderDescriptor desc= (ReferenceProviderDescriptor) it.next();
                     ReferenceSelectionAction action= new ReferenceSelectionAction(desc, fEditor);
                     if (action.isEnabled())
                         menu.add(action);
                 }
                 manager.appendToGroup(GROUP_QUICKDIFF, menu);

                 // create restore menu if this action is enabled
 if (isConnected()) {
                     for (int i= 0; i < fRestoreActions.length; i++) {
                         fRestoreActions[i].update();
                     }
                     // only add block action if selection action is not enabled
 if (fRestoreActions[0].isEnabled())
                         manager.appendToGroup(GROUP_RESTORE, fRestoreActions[0]);
                     else if (fRestoreActions[1].isEnabled())
                         manager.appendToGroup(GROUP_RESTORE, fRestoreActions[1]);
                     if (fRestoreActions[2].isEnabled())
                         manager.appendToGroup(GROUP_RESTORE, fRestoreActions[2]);
                     if (fRestoreActions[3].isEnabled())
                         manager.appendToGroup(GROUP_RESTORE, fRestoreActions[3]);
                 }
             }
         }
     };

     /*
      * @see org.eclipse.ui.IEditorActionDelegate#setActiveEditor(org.eclipse.jface.action.IAction, org.eclipse.ui.IEditorPart)
      */
     public void setActiveEditor(IAction action, IEditorPart targetEditor) {
         fProxy= action;
         removePopupMenu();
         if (targetEditor instanceof ITextEditor) {
             fEditor= (ITextEditor)targetEditor;
         } else
             fEditor= null;
         for (int i= 0; i < fRestoreActions.length; i++) {
             fRestoreActions[i].setEditor(fEditor);
         }
         setPopupMenu();
     }

     /**
      * Removes the ruler context menu listener from the current editor.
      */
     private void removePopupMenu() {
         if (!(fEditor instanceof ITextEditorExtension))
             return;
         ((ITextEditorExtension)fEditor).removeRulerContextMenuListener(fListener);
     }

     /**
      * Installs a submenu with <code>fEditor</code>'s ruler context menu that contains the choices
      * for the quick diff reference. This allows the toggle action to lazily install the menu once
      * quick diff has been enabled.
      */
     private void setPopupMenu() {
         if (!(fEditor instanceof ITextEditorExtension))
             return;
         ((ITextEditorExtension)fEditor).addRulerContextMenuListener(fListener);
     }

     /**
      * States whether this toggle action has been installed and a incremental differ has been
      * installed with the line number bar.
      *
      * @return <code>true</code> if a differ has been installed on <code>fEditor</code>.
      */
     boolean isConnected() {
         if (!(fEditor instanceof ITextEditorExtension3))
             return false;
         return ((ITextEditorExtension3)fEditor).isChangeInformationShowing();
     }

     /*
      * @see org.eclipse.ui.IActionDelegate#run(org.eclipse.jface.action.IAction)
      */
     public void run(IAction action) {
         fProxy= action;
         if (fEditor == null)
             return;

         if (fEditor instanceof ITextEditorExtension3) {
             ITextEditorExtension3 extension= (ITextEditorExtension3)fEditor;
             extension.showChangeInformation(!extension.isChangeInformationShowing());
         }
     }

     /*
      * @see org.eclipse.ui.IActionDelegate#selectionChanged(org.eclipse.jface.action.IAction, org.eclipse.jface.viewers.ISelection)
      */
     public void selectionChanged(IAction action, ISelection selection) {
         fProxy= action;
     }

     /*
      * @see org.eclipse.ui.texteditor.IUpdate#update()
      */
     public void update() {
         if (fProxy == null)
             return;
         if (isConnected())
             fProxy.setText(QuickDiffMessages.quickdiff_toggle_disable);
         else
             fProxy.setText(QuickDiffMessages.quickdiff_toggle_enable);
     }

 }

